Dr. Penn would be pleased to note that the stated United Network for Organ Sharing (UNOS) interpretation of Scientific Registry of Transplant Recipients (SRTR) data on the risk of donor central nervous system (CNS) tumor transmission is identical to his initial opinion published in 1991 (1–4). The manner in which the overall risk of tumor transmission is reported deserves comment. Data regarding the risk of CNS tumor transmission is only relevant when expressed as the following proportion: the number of transplant recipients who experience donor CNS tumor transmission out of the entire population of transplant recipients who receive organs from donors with CNS tumors. Expression of this risk using other denominators (such as all solid-organ donors) can be misleading because the overwhelming majority of the population is not at risk for donor-related CNS tumor transmission. UNOS presentation of data in this manner only means one thing: that donors with a history of CNS tumors are relatively infrequent, and the risk of transmission of a CNS tumor in most patients with CNS tumors is also infrequent.
UNOS publications have generally held that the risk of tumor transmission in transplant recipients is small. It is small however, because of two reasons. First, donors with CNS tumors are very infrequent. Second, among donors with CNS tumors, those that are high risk for transmission actually represent a minority of this group of donors. The transplant community must be sophisticated enough, however, to understand that a high-risk population does exist and that great care should be used to identify these donors and avoid use of their organs. When this level of sophistication does not exist, the risk of tumor transmission will be real.
Definition of risk factors for tumor transmission requires a critical mass of recipients experiencing these events. For relatively rare events, event-based registries have substantial advantages over mandatory reporting registries, where capture rates are always at issue. The Israel Penn International Transplant Tumor Registry (IPITTR) has the only data set capable of defining risk factors for tumor transmission because it has a substantial number of recipients with donor CNS tumor transmission. In contrast, the paucity of observed donor CNS tumor transmission events in the Australian New Zealand and SRTR registries precludes such analyses. Furthermore, IPITTR collects substantially more detailed information, including pathology reports, and therefore data collected on individual events is substantially more robust. Mandatory reporting registries simply cannot require such detailed reporting from all centers. This issue, more than any other, highlights the importance of both types of registries in answering questions regarding infrequent events such as donor-related CNS tumor transmission.
The importance of defining risk factors for donor CNS tumor transmission arises when a transplant team is under time pressure to make a decision about using organs from a donor with a history of CNS tumor. The IPITTR is consulted relatively frequently on these issues, and the purpose of our ongoing work on this issue is to better define those donors with a history of CNS tumors who represent the highest risk of tumor transmission so we can better advise the transplant community in a consultative setting. The IPITTR is continuing to collect highly detailed data on patients in the United States and the international transplant community on patients receiving organs from donors with a history of CNS tumors to better define those donors at highest risk of tumor transmission. Ongoing updates of these data with scientific publication will improve the consultative services on these donors to the international transplant community.
Joseph F. Buell
Thomas M. Beebe
Thomas G. Gross
Michael J. Hanaway
Rita R. Alloway
M. Roy First
E. Steve Woodle
FACS, The Israel Penn International Transplant Tumor Registry
The University of Cincinnati
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